Vehicle seat belt systems typically include a length of belt defining a lap belt portion that extends horizontally across the lower torso and a shoulder belt portion that extends diagonally across the upper torso. The outboard end of the shoulder belt portion slides through a ring mounted high on the vehicle pillar and is wound within a retractor mounted low on the vehicle pillar. The outboard end of the lap belt portion is suitably mounted low on the pillar, seat, or on the floor. A latch plate is provided at the juncture of the inboard end of the shoulder belt portion and lap belt portion and is latched in a buckle mounted inboard the seat.
In its simplest form, the seat belt system utilizes a retractor with a spring biased reel that merely winds the belt taut about the occupant, and an inertia locking mechanism that locks that reel against unwinding rotation upon onset of a deceleration event. In more sophisticated seat belt systems, the seat belt system utilizes a pre-tensioner that will react to the deceleration event by pulling or reeling in a length of the belt to tighten the belt about the occupant before locking against unwinding rotation. The pre-tensioner may be provided in the reel, in the buckle mounting, or in the anchor mounting the outboard end of the lap belt. In addition, the more sophisticated systems have a load limiter that limits the load experienced by the belted occupant. This load limit feature is provided by a clutch or other device that will allow the belt to be paid out in a controlled manner when the load limit is reached. The load limiter can be provided in the retractor or at the buckle or at the mounting of the outboard ends of the lap or shoulder belt portions.
It would be desirable to provide a test apparatus in which the various components of a vehicle seat belt system could be mounted and tested to collect data related to the performance of an overall system configured from various components such as a retractor, a pre-tensioner, and a load limiter.